Step 1: Calculate the average net profit.
Average net profit = \(\frac{6000 + 13000 + 8000}{3} = \frac{27000}{3} = 9,000\)
Step 2: Calculate goodwill.
Goodwill at two years' purchase = \( 2 \times 9,000 = 18,000 \)
Step 3: Conclusion.
Thus, the correct answer is (A) Rs. 27,000.
Final Answer:
\[
\boxed{\text{Rs. 27,000}}
\]